It is a common requirement of numerous bulk material processes to cool or dry the product at some intermediate or final stage of production. As implied by the name, the product to be cooled or dried is typically produced in bulk quantities and consequently requires a cooling or drying apparatus that is capable of processing large quantities of material in an efficient, continuous and uniform manner. Typical bulk material cooler/dryer designs achieve the desired cooling or drying effect by forcefully flowing a gas, such as air, through the cooling/drying chamber and consequently through the bulk material that is contained therein. If a general cooling effect is desired, cool air is forced through the chamber, whereas if a drying effect is desired, warm or hot air is necessarily flowed through the chamber.
Given a cooling/drying air stream of constant temperature and a constant air flow rate, relatively accurate control of the bulk material flow rate through the cooling/drying chamber is required in order to maintain a constant temperature or degree of dryness of the material that is discharged from the chamber. Furthermore, in addition to the constant flow rate of bulk material through the cooling/drying chamber, it is also necessary that the bulk material be generally uniformly distributed within chamber as it flows therethrough.
It will be appreciated that under steady state conditions, control of the effective bulk material flow rate through the cooling/drying chamber can be monitored and maintained via control of the bulk material level within the main cooling/drying chamber. In basic terms, control of the bulk material level within the chamber can be accomplished by controlling both the flow rate of material into the chamber and the flow rate of material out of the chamber.
In practice, the primary difficulty involves the design of a practical bulk materials cooling/drying apparatus which provides adequate control of the outlet flow rate of material from the chamber, while simultaneously providing the degree of uniform material distribution required for efficient and effective operation of the cooling/drying apparatus. Furthermore, it is highly desirable from a maintenance perspective that the apparatus provide a simple and effective means of cleaning or emptying the cooling/drying chamber and its associated components, which typically entails a chamber outlet design which can be rapidly switched between a normal operating configuration and a clean-out configuration.
While a number of bulk materials cooling/drying chambers employing a variety of chamber inlet/outlet configurations have been disclosed in prior art submissions, such as U.S. Pat. No. 4,887,364, a cooling/drying apparatus continues to be needed which is simple in design, yet provides optimal performance with regard to the control of material distribution within the cooling/drying chamber and the associated flow rate of material therethrough. In addition, provision within the apparatus for simple and rapid clean-out of residual particulate material from the cooling/drying chamber and associated components is also a key requirement of the bulk materials manufacturing sector. Finally, it is important that the cooling/drying apparatus be provided with a material discharge assembly that handles the bulk material in such a manner that the material is not damaged.